4.54609

1 imperial gallon is equivalent to 4.54609 litter. This definition is used in some Commonwealth countries and Ireland, and is based on the volume of 10 pounds of water at 62 °F. The imperial fluid ounce is defined as 1 160 of an imperial gallon. On 1 January 2000, it ceased to be a legal unit of measure within the United Kingdom for economic, health, safety or administrative purposes.